The American College of Surgeons Surgical Risk Calculator performs well for pulmonary resection: A validation study

Objective: The American College of Surgeons National Surgical Quality Improvement Program Surgical Risk Calculator (NSQIP SRC) was developed to estimate the risk of postoperative morbidity and mortality within 30 days of an operation. We sought to externally evaluate the performance of the NSQIP SRC for patients undergoing pulmonary resection. Methods: Patients undergoing pulmonary resection at our center between January 2016 and December 2018 were included. Using data from our institution's prospectively maintained Society of Thoracic Surgeons General Thoracic Database, we identified 2514 patients. We entered requisite patient demographic information, preoperative risk factors, and procedural details into the online calculator. Predicted performance of the calculator versus observed outcomes was assessed by discrimination (concordance index [C-index]) and calibration. Results: The observed and predicted probabilities of any complication were 8.3% and 9.9%, respectively, and of serious complications were 7.4% and 9.2%, respectively. Observed and predicted 30-day mortality were 0.5% and 0.9%, respectively. The C-index for readmission was 0.644; the C-indices corresponding to all other outcomes in the NSQIP SRC ranged from 0.703 to 0.821. Calibration curves indicated excellent calibration for all binary end points, with the exception of renal failure (predicted underestimated observed probabilities), discharge to a nursing or rehabilitation facility (overestimated), and sepsis (overestimated). Correlation between predicted and observed length of stay was moderate (Spearman coefficient, 0.562), and calibration was good. Conclusions: Except for readmission, renal failure, discharge to a location other than home, and sepsis, the NSQIP SRC can be used to reasonably predict postoperative complications in patients undergoing pulmonary resection.